Buoyancy-Induced Flow in Open Rotating Cavities

Abstract

Buoyancy-induced flow can occur in the cavity between the co-rotating compressor disks in gas-turbine engines, where the Rayleigh numbers can be in excess of 1012. In most cases the cavity is open at the center, and an axial throughflow of cooling air can interact with the buoyancy-induced flow between the disks. Such flows can be modeled, computationally and experimentally, by a simple rotating cavity with an axial flow of air. This paper describes work conducted as part of ICAS-GT, a major European research project. Experimental measurements of velocity, temperature, and heat transfer were obtained on a purpose-built experimental rig, and these results have been reported in an earlier paper. In addition, 3D unsteady CFD computations were carried out using a commercial code (Fluent) and a RNG k‐ε turbulence model. The computed velocity vectors and contours of temperature reveal a flow structure in which, as seen by previous experimenters, “radial arms” transport cold air from the center to the periphery of the cavity, and regions of cyclonic and anticyclonic circulation are formed on either side of each arm. The computed radial distribution of the tangential velocity agrees reasonably well with the measurements in two of the three cases considered here. In the third case, the computations significantly overpredict the measurements; the reason for this is not understood. The computed and measured values of Nu for the heated disk show qualitatively similar radial distributions, with high values near the center and the periphery. In two of the cases, the quantitative agreement is reasonably good; in the third case, the computations significantly underpredict the measured values.

Advanced Modeling of Flow and Heat Transfer in Rotating Disk Cavities Using Open-Source Computational Fluid Dynamics

“…For example, Sun et al [35] found considerable difference in heat transfer predictions between LES and URANS. Owen et al [36] showed mixed results from URANS modelling: agreement with disc heat transfer measurements was found for some conditions, but large differences at other conditions. Therefore, this open question is further considered here.…”

Advanced Modelling of Flow and Heat Transfer in Rotating Disc Cavities Using Open-Source CFD

“…For example, Sun et al [36] found considerable difference in heat transfer predictions between LES and URANS. Owen et al [37] showed mixed results from URANS modelling: agreement with disc heat transfer measurements was found for some conditions, but large differences at other conditions. Therefore, this open question is further considered here.…”

Computational fluid dynamics for turbomachinery internal air systems

“…However, limitations of the laminar model were recognized. Smout et al (2002), Wong (2002) and Owen et al (2006) have reported the use of conventional k-3 turbulence models in unsteady three-dimensional simulations, but the information available in the open literature is limited. Both Wong's and Owen et al's comparisons with heat transfer measurements gave mixed results.…”